Photolyses of solutions containing organomercury compounds (HgR2) in the presence of C-60 fullerene have been investigated by Fourier transform time-resolved EPR (FT TR EPR) and continuous-wave EPR (CW EPR) techniques. By FT TR EPRI both electron-spin-polarized C-3(60) (A polarization) and electron-spin-polarized adducts (C60R)-C-. (E/A + E polarization) are observed. The CW EPR spectra of the (C60R)-C-. radicals under steady-state irradiation also exhibit some electron-spin polarization. The chemically induced dynamic electron polarization (CIDEP) in the FT TR EPR experiments is explained by the following series of steps. Photolysis initially causes cleavage of the organomercury compounds into radicals that add to C-60 to form (C60R)-C-.. The latter combine to form the dimers, [C60R](2), which are thermally stable and accumulate in the samples. in all of the reported experiments, a certain quantity of dimers is produced by photolysis before the EPR spectra are acquired. Ln the FT TR EPR experiments, laser excitation produces C-3(60) by excitation of C-60 and (C60R)-C-. by photocleavage of the dimers. The observed E/A CIDEP patterns at short (<1 mu s) delays after the laser flash are proposed to be a result of the creation of polarization through the radical-pair mechanism (RPM) resulting from the interactions of two (C60R)-C-. radicals (geminate or free) formed from the photocleavage of [C60R](2) dimers. The additional E polarization observed at later times (>1 mu s) is proposed to result from the interaction of C-3(60) With C60R radicals, creating E polarization through the radical-pair-triplet mechanism (RPTM). The polarization observed in the CW EPR experiments is attributed to the maintenance of polarization through the radical lifetime because of the extremely long spin-lattice relaxation of the (C60R)-C-. radicals. The latter conclusion is consistent with the very small (50 mG) Line widths of the adduct radicals. An upper limit for the bond energy of the [C60R](2) dimers of 226 kJ/mol is established by the observation of the CIDEP of (C60R)-C-. radicals when 532-nm excitation is employed. The role of multiple adducts in the observed FT TR EPR spectra is discussed.